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999 / 112 / 911

  • This topic has 9 replies, 1 voice, and was last updated 12 years ago by paraHO.
Viewing 10 posts - 1 through 10 (of 10 total)
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  • #56501 Reply

    Hi Folks, I am writing a book for Search & Rescue and have a section with deals with MTPAS and the special emergency setup initiation in GSM mobiles.

    Does anyone know how MTPAS differs from ACCOLC and if 112/999 is preprogrammed in the mobile can it still override the system, Thanks, Lyle

    #56502 Reply

    Dear, Lyle!
    As I know (from, MTPAS differs from ACCOLC only by organisation procedures (On what level decision is taken) and more flexible assignment of access class on local level. MTPAS and ACCOLC are British internal procedures, based on standard GSM Access Class Control.
    MS Access Class is stored on SIM and I am doubting that all British people want to re-programme their SIM (more so this hardly possible). And if however 1-2 malicious subscribers will preprogramm SIM, it not will cause a global network congestion.

    #56503 Reply

    Dear Pan,
    Thank you for your prompt reply; much appreciated! Lyle

    #56504 Reply

    Also in UK operators use part of IMSI to identify subscriber’s Access Control Class to prevent accidental or malicious alteration of the data in SIM EFACC allocation.

    #56505 Reply

    Hi paraHO, the bottom libne is that I would like to state that dialling 112 in Europe & 911 in the US overrides any systems such as ACCOLC or MTPAS and WPS respectively. Do you know if this is correct? Plus do you know what the differences are between ACCOLC & MTPAS are?

    #56506 Reply

    Lyle, ACCOLC and MTPAS are British internal procedures as Pan mentioned.

    ACCOLC (Access Overload Control) is being phased out in 2009. Where the ACCOLC event occurs the cell and necessary surrounding cells are taken out of use to deal with emergency. 999 or 112 calls MIGHT still be made isf the a mobile phone is “within radio range” of other cells not affected by the ACCOLC is imposed. ACCOLC is not a radio dampening procedure it merely prevents access to the network using network blocking of unprioritized non-ACCOLC register
    SIM users. Also the Access Control Classes 0-9 and 11-15 were more emphasized. Also certain types of emergency were assigned Gold Silver and Bronze Command authority and priority. Read: (, how this authroity comes from a centralised authority and then implemented locally.

    MTPAS (Mobile Telecommunication Privileged Access Scheme) is similar to ACCOLC but priority is given to privileged users as opposed to ordinary (unprivileged users). Unlike ACCOLC, a MTPAS cannot disable the network but increases resources to MTPAS privileged users. But 999 and 112 calls can still be made by unprivileged users in parallel to an MTPAS event happening.
    The network is left to implement MTPAS the best way possible. Gold Commander actions MTPAS events with the network at the local level.

    For US issues for 911 look to: ( and

    #56507 Reply

    Dears, Lyle and ParaHo!
    Additionally to ParaHo post I want to notice that both either ACCOLC or MTPAS are not GSM standards. They only use GSM standard feature, namely Access Class, for their own aims. Classes 0 to 9 are destined for ordinary subscribers (randomly allocated to SIM), 11 to 15 – for PLMN Staff, Emergency Services, Police etc. If network broadcasts Access restrictions for classes 0-9 on the all cells of some area, then ordinary subscribers don’t get access to network in this area. Only emergency calls is allowed. When network additionally broadcasts Access Class = 10, then emergency calls are not allowed for ordinary subscribers. There are no possibilities to override Access control for ordinary subscriber. However, ACCOLC or MTPAS are not only access control but also the “people giving orders” and “people carrying out” these orders. From this point of view any accidents are possible.

    #56508 Reply

    Additional to Pan, I check a ‘UK’ emergency response how MTPAS stated in manual for local level emergency. It say:

    2.3.1 Mobile Telecommunications Privileged Access Scheme (MTPAS)
    MTPAS (previously Access Control Overload- ACCOLC) permits the major mobile
    phone companies to reserve exclusive channels for use by the Emergency Services
    and Local Authorities in the event of a major incident. However it should be noted:
    • The facility is rarely invoked and is very expensive.
    • Decision to activate MTPAS is made by the mobile phone companies on the
    request of the Police only.
    • MTPAS would only be activated for limited ‘cells’ normally the immediate vicinity
    of the scene of the incident.
    • Facility disrupts normal subscribers who may be involved in the incident and need
    to contact emergency services.

    The last point under 2.3.1 say ‘disrupt’ meaning affects (stops) contacting emergency services (999/112 calls) when MTPAS deployed on cells.

    #56509 Reply

    Well, paraHO. It is new merry game:
    And additionally to paraHo: blablablablablablablablablablablablablab……………….. 🙂

    #56510 Reply

    Pan you made me laugh with what you say 🙂

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